title: Contact sensitization to calocephalin, a sesquiterpene lactone of the guaianolide type from cushion bush (Leucophyta brownii, Compositae).
abstract: BACKGROUND
  Cushion bush [Leucophyta brownii Cass. = Calocephalus brownii (Cass.) F. Muell.] is an Australian Compositae shrub that has been introduced into Scandinavia as a pot plant. The first case of sensitization occurred in a gardener, and the main allergen was identified as the guaianolide calocephalin.
  
  
  OBJECTIVE
  To present the identification of the main allergen, and to assess the prevalence of sensitization to calocephalin in Compositae-allergic patients.
  
  
  METHODS
  Calocephalin was isolated from a dichloromethane extract of aerial parts of cushion bush. Calocephalin 0.1% ethanol was included in the plant series in Malmö, Sweden, and Odense, Denmark.
  
  
  RESULTS
  Nuclear magnetic resonance (NMR) analysis of calocephalin resulted in a revision of its chemical structure to 4α-acetoxy-1α,2α-epoxy-5α,10αH-guai-11(13)-en-12,8β-olide. The prevalence of patch test positivity was up to 28% in aimed patch testing. Despite strongly positive patch test reactions, the relevance was unknown in the majority of cases, and only 1 person was occupationally sensitized.
  
  
  CONCLUSIONS
  Calocephalin is a potent contact allergen, but, as cushion bush is a low-maintenance pot plant, primary sensitization is most likely to occur through occupational exposure. Positive reactions in Compositae-sensitive persons probably occur because of cross-reactivity, and patients should be warned about contact with cushion bush plants.
authors.affiliation: Department of Dermatology and Allergy Centre, Odense University Hospital, University of Southern Denmark, DK-5000, Odense C, Denmark.
authors.forename: Evy
authors.initials: E
authors.lastname: Paulsen
authors.forename: Lars P
authors.initials: LP
authors.lastname: Christensen
authors.forename: Monica
authors.initials: M
authors.lastname: Hindsén
authors.forename: Klaus E
authors.initials: KE
authors.lastname: Andersen
mesh_terms: D000328:Adult; D000368:Aged; D000485:Allergens / Q000009:adverse effects* / Q000302:isolation & purification*; D019659:Asteraceae / Q000009:adverse effects* / Q000737:chemistry*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015394:Molecular Structure; D010328:Patch Tests / Q000379:methods; D010936:Plant Extracts / Q000009:adverse effects* / Q000302:isolation & purification*; D045789:Sesquiterpenes, Guaiane / Q000009:adverse effects* / Q000302:isolation & purification*
chemical_list: D000485:Allergens; D010936:Plant Extracts; D045789:Sesquiterpenes, Guaiane; C586418:calocephalin
keywords: Calocephalus brownii; Leucophyta brownii; allergic contact dermatitis; calocephalin; guaianolides; occupational; patch testing; sesquiterpene lactones